Evolution: genetics in high altitude humans (Evolution)

by David Turell , Saturday, February 10, 2024, 20:06 (77 days ago) @ David Turell

Tibetan genes not the same as Andean genes:

https://medicalxpress.com/news/2024-02-harnessing-human-evolution-advance-precision.html

"...reveals that a gene variant in some Andean people is associated with reduced red blood cell count at high altitudes, enabling them to safely live high in the mountains in low-oxygen conditions.

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"Her previous research showed that many mountain-dwelling Tibetans exposed to low-oxygen situations are born with innate mechanisms that protect them from poor outcomes at high altitude, including the overproduction of red blood cells. Part of this is due to changes in the regulation of the EPAS1 gene, which lowers hemoglobin concentrations by regulating the pathway that responds to changing oxygen levels. Advances in genetics have shown that modern Tibetans received this genetic advantage from their ancestors who mixed with archaic humans living in Asia tens of thousands of years ago—a unique evolutionary history confined to this population.

"For her latest research, Dr. Simonson, who is also the John B. West Endowed Chair in Respiratory Physiology and associate professor in the Division of Pulmonary, Critical Care, Sleep Medicine & Physiology at UC San Diego School of Medicine, zoomed in on the EPAS1 region of the genome. She and her team focused on a mutation in the gene that is present in some people living in the Andes but is absent in all other human populations. When they scanned whole Andean genomes, they found a pattern surrounding this variant suggesting that the genetic change, which alters only a single amino acid in the protein product, happened by chance, relatively recently (from 9,000 to 13,000 years ago), and spread very quickly through hundreds of generations within the Andean population.

"Similar to Tibetans, the EPAS1 gene is associated with lower red blood cell count in Andeans who possess it. However, the researchers were surprised to find that the variant works in a completely different way from the Tibetan version of the gene; rather than regulating its levels, the Andean variant changes the genetic makeup of the protein, altering the DNA in every single cell.

"'Tibetans have, in general, an average lower hemoglobin concentration, and their physiology deals with low oxygen in a way that doesn't increase their red blood cells to excessively high levels. Now we have the first signs of evidence that Andeans are also going down that path, involving the same gene, but with a protein-coding change. Evolution has worked in these two populations, on the same gene, but in different ways," said Simonson.

"This study exemplifies a current approach in research that connects genetic targets of natural selection with complex disease genes—understanding, for example, how natural genetic variation contributes to adaptive and maladaptive responses to low oxygen, as this study reveals."

Comment: two different ways for different mutations at work. Just two examples. Would other high-altitude folks have different results? This shows human still adapt as necessary, but I think true speciation is over.